According to Alison of Bath Body Supply, "a lip plumper is a cosmetic product used to make lips appear fuller. In appearance, it ranges from translucent to opaque and tinted. Lip plumpers are used by those with thinner lips when full, "pouty" lips are desired. These products typically work by irritating the thin, delicate skin of the lips with ingredients like menthol, cayenne or cinnamon. This makes the lips swell slightly, which may also diminish the appearance of fine lines in that area. Other perceived benefits include stimulating collagen production and moisturizing. A lip plumper's effects are temporary, so it must be reapplied throughout the day to maintain the results."
She posted this recipe to create this Red Hot Lip Gloss on her blog DIY Skincare. In this recipe, Alison has for the first ingredient is Natural Lip Balm Base (For Pots) which you can purchase through Bath Body Supply but if you have your own recipe you could probably subsitute.